The solid state power controller (SSPC) is a solid state device that has been relied upon to replace the traditional circuit breaker in certain applications, including aircraft electrical power distribution. It is desired for SSPC to have the same trip curve as the circuit breaker. However, the most commonly used trip criterion for SSPC is I2t, which is close to circuit breaker only when the current is much higher than the rated current. The I2t trip cannot be used independently; instead, it is typically combined with other modifications, like no-trip threshold, thermal memory, etc. Even with all these modifications, it is still difficult to match the trip curve with circuit breaker when current is within 100%˜150%.